Climate Zone 6B - Cold, Dry
Short warm summers and long cold winters with low humidity. This climate zone encompasses parts of Montana, Wyoming, Idaho, Colorado and includes major cities like Helena, Casper, Bozeman, Jackson.
Common Questions About Zone 6B
Zone 6B definition
This page explains what IECC climate zone 6B means in HVAC and building-code terms.
Cities in zone 6B
Use the city examples below to answer common lookup searches for this zone.
Heating and cooling profile
See whether zone 6B is heating-dominant, cooling-dominant, or balanced.
HVAC requirements
Compare design temperatures, degree days, code requirements, and equipment guidance for this zone.
What IECC Climate Zone 6B Means
Temperature class
Cold (Zone 6)
Moisture class
Dry (B)
Load priority
Heating-dominant
Quick definition
Short warm summers and long cold winters with low humidity.
Common City Lookups for Zone 6B
| City | IECC zone answer | Why it matters |
|---|---|---|
| Helena | Helena is commonly treated as IECC climate zone 6B in this guide. | Extreme heating loads |
| Casper | Casper is commonly treated as IECC climate zone 6B in this guide. | Extreme heating loads |
| Bozeman | Bozeman is commonly treated as IECC climate zone 6B in this guide. | Extreme heating loads |
| Jackson | Jackson is commonly treated as IECC climate zone 6B in this guide. | Extreme heating loads |
Design Temperatures
Winter Design Temperatures
Used for heating load calculations and equipment sizing
Summer Design Temperatures
Used for cooling load calculations and equipment sizing
Heating & Cooling Degree Days
Heating Degree Days (HDD)
Base 65°F. Higher numbers indicate more heating requirements and longer heating seasons.
Cooling Degree Days (CDD)
Base 65°F. Higher numbers indicate more cooling requirements and longer cooling seasons.
HVAC System Considerations
Key Considerations
- •Extreme heating loads
- •Minimal cooling needs
- •High altitude effects
- •Equipment derating required
- •Freeze protection critical
Common Equipment
- ✓High-efficiency gas furnaces
- ✓Boilers
- ✓Radiant heating
- ✓Wood/pellet supplemental heat
Energy Code Requirements
Equipment Efficiency
- ⚠AFUE 90+ for furnaces
- ⚠High-performance windows
- ⚠Continuous insulation
- ⚠Air sealing requirements
Insulation Requirements
Quick Reference
Calculate Load
Use our load calculators with the design temperatures and requirements specific to Zone 6B.